If you need a quick heating pad and don't have access to the usual, plug-in version, try this: grab a sock (tall ones or tube socks work best) and fill it 75% full with dry rice. Tie the top of the sock (twisty-ties or rubber bands work well here) and microwave the sock for 2 minutes. Remove the sock, make sure it's not too hot, and use it as a heating pad. It will stay warm for about 45 minutes.